Energy-conserving schemes for wind farm aerodynamics

Computational demands compel researchers to use coarse grids for the study of wind farm aerodynamics, which necessitates the use of accurate numerical schemes. Energy- conserving (EC) schemes are designed to enforce the conservation of Kinetic Energy (KE), an invariant property of incompressible flows. These schemes are numerically stable and free from artificial dissipation, even on coarse grids and could be used as an alternative to high-order pseudo-spectral schemes. This article details tests on EC schemes in the context of Large Eddy Simulations (LES). Results suggest that the accuracy of EC schemes is influenced by the Subgrid Scale model used for the LES. EC methods use central schemes that lead to dispersion, which is more apparent with a less-dissipative Scale Similarity model. Whereas, the purely dissipative Smagorinsky's model reduces the dispersion and generates a smoother solution but at the cost of accuracy in terms of predicting the KE. Although the impact of EC schemes and SGS models on the LES of wind farms is yet to be assessed, a simple LES of a model wind farm uncovers that EC schemes are quite suitable for wind farm aerodynamics.